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BLOCK DIAGRAM

•

Integrated 0.1

Ω

Power MOSFET

•

–3V to –15V Operation

•

Programmable

Electronic Circuit

Breaker

•

Digital Programmable

Current Limit from 0A

to 3A

•

Programmable

Maximum Output

Current from 0A to 4A

•

Programmable On

Time

•

Fixed 2% Fault Duty

Cycle

•

Thermal Shutdown

•

Fault Output Indicator

•

Power SOIC Package

–3V to –15V Hot Swap Power Manager

FEATURES

DESCRIPTION

UCC2920

UCC3920

PRELIMINARY

UDG-96235-1

The UCC3920 Low RDSon Hot Swap Power Manager provides complete power man-

agement, hot swap capability, and circuit breaker functions. The only component

needed to operate the device, other than supply bypassing, is the fault timing capaci-

tor, CT. All control and housekeeping functions are integrated and externally program-

mable. These include the fault current level, maximum output sourcing current, maxi-

mum fault time, and start up delay. In the event of a constant fault, the internal fixed

2% duty cycle ratio limits the average output power.

The internal 3 bit DAC allows programming of the fault level current from 0mA to

500mA with 250mA resolution, and from 500mA to 3A with 500mA resolution. The

IMAX control pin sets the maximum sourcing current to 1A above the fault level when

driven low, and to a full 4A when driven high for applications which require fast output

charging.

When the output current is below the fault level, the output MOSFET is switched on

with a nominal resistance of 0.1

Ω. When the output current exceeds the fault level or

the maximum sourcing level, the output remains on, but the fault timer starts charging

CT. Once CT charges to a preset threshold, the switch is turned off, and remains off

for 50 times the programmed fault time. When the output current reaches the maxi-

mum sourcing level, the MOSFET transitions form a switch to a constant current

source, regulating the output current at a constant level.

Other features include an Open Drain Fault Output Indicator, Thermal Shutdown, Un-

dervoltage Lockout, –3V to –15V operation, and a low thermal resistance Small Out-

line Power Package. All level shifting is done internally, which means that the DAC,

IMAX and Shutdown Inputs can be driven form the logic supply. The fault output is

also referenced to the logic GND, so this can easily interface back to the logic supply.